(a) Field of the Invention
The present invention relates to a liquid crystal display (LCD), and more particularly to a LCD having a dual bank data driver structure and a driving method thereof.
(b) Description of the Related Art
The LCD is increasingly being used for the display device in televisions, personal computers and various other consumer appliances. The superior qualities of the LCD, such as low power consumption, thin profile, high resolution, light weight, etc., makes it be a future substitute for the traditional CRT displays.
LCDs apply an electric field to liquid crystal material of anisotropic dielectricity injected between two substrates to form a liquid crystal layer. The two substrates are arranged substantially parallel to one another having a predetermined gap therebetween, and the amount of light permeating the substrates is controlled by the intensity of the electric field applied to the liquid crystal material.
The LCD typically comprises a LCD panel including two substrates on which are formed a plurality of gate lines and data lines, a switching transistor and a pixel defined by the intersection of the gate lines and data lines. The LCD also comprises a gate driver that turns on each of the gate lines in sequence by applying a scanning signal; and a data driver (also called a source driver) that applies grey voltage corresponding to color signals to the data lines of the LCD panel in units of lines. The data driver and the gate driver are comprised of a plurality of data driver ICs and gate driver ICs, respectively.
If the electric field is applied to the liquid crystal layer, in the same direction continuously, the liquid crystal tends to degrades. Accordingly, image signals must be driven alternately between positive and negative values. Such a drive method is called an inversion driving method. Among the different types of the inversion driving methods, a frame inversion method inverts the image signals in units of frames, a line inversion method inverts the image signals in units of lines, and a dot inversion method inverts the image signals in units of pixels. When using a frame inversion method or a line inversion method, however, it is difficult to attain an optimal picture quality because of crosstalk and flicker problems.
Accordingly, a method recently used alternates the polarity of an image signal for common electrode voltage, supplied from the data driver ICs, between a positive polarity (+) and a negative polarity (-) in units of pixels. In more detail, after arranging the data driver ICs in a row on one of the two substrates of the LCD panel and electrically connecting a data line to an output terminal of each of the data driver ICs (hereinafter referred to as a single bank structure), a grey voltage output from each of the output terminals of the data driver ICs is controlled to change from positive to negative while being applied to the data lines, thereby alternating the polarity of the pixels from positive to negative.
In addition to the above typical single bank structure LCD, there has been developed a dual bank structure LCD in which data driver ICs are arranged on both the upper and lower substrates of the LCD panel. In the dual bank structure, odd (or even) data lines are connected to upper data driver ICs and even (or odd) data lines are connected to lower data driver ICs. However, with the dual bank structure LCD, as with the single bank structure LCD, if grey voltage output from the output terminals of the data drive ICs is applied to the data lines alternating from positive to negative, polarities of the pixels are inverted in (+)(+) and (-)(-) cycles. As a result, full dot inversion is not realized.